// ASM: a very small and fast Java bytecode manipulation framework
// Copyright (c) 2000-2011 INRIA, France Telecom
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//
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//    notice, this list of conditions and the following disclaimer in the
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//    this software without specific prior written permission.
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package xyz.noark.asm.signature;

import xyz.noark.asm.Opcodes;

/**
 * A visitor to visit a generic signature. The methods of this interface must be
 * called in one of the three following orders (the last one is the only valid
 * order for a {@link SignatureVisitor} that is returned by a method of this
 * interface):
 *
 * <ul>
 * <li><i>ClassSignature</i> = ( {@code visitFormalTypeParameter}
 * {@code visitClassBound}? {@code
 *       visitInterfaceBound}* )* ({@code visitSuperclass}
 * {@code visitInterface}* )
 * <li><i>MethodSignature</i> = ( {@code visitFormalTypeParameter}
 * {@code visitClassBound}? {@code
 *       visitInterfaceBound}* )* ({@code visitParameterType}*
 * {@code visitReturnType} {@code
 *       visitExceptionType}* )
 * <li><i>TypeSignature</i> = {@code visitBaseType} | {@code visitTypeVariable}
 * | {@code
 *       visitArrayType} | ( {@code visitClassType} {@code visitTypeArgument}* (
 * {@code
 *       visitInnerClassType} {@code visitTypeArgument}* )* {@code visitEnd} ) )
 * </ul>
 *
 * @author Thomas Hallgren
 * @author Eric Bruneton
 */
public abstract class SignatureVisitor {

	/** Wildcard for an "extends" type argument. */
	public static final char EXTENDS = '+';

	/** Wildcard for a "super" type argument. */
	public static final char SUPER = '-';

	/** Wildcard for a normal type argument. */
	public static final char INSTANCEOF = '=';

	/**
	 * The ASM API version implemented by this visitor. The value of this field
	 * must be one of {@link Opcodes#ASM4}, {@link Opcodes#ASM5},
	 * {@link Opcodes#ASM6} or {@link Opcodes#ASM7}.
	 */
	protected final int api;

	/**
	 * Constructs a new {@link SignatureVisitor}.
	 *
	 * @param api the ASM API version implemented by this visitor. Must be one
	 *            of {@link Opcodes#ASM4}, {@link Opcodes#ASM5},
	 *            {@link Opcodes#ASM6} or {@link Opcodes#ASM7}.
	 */
	public SignatureVisitor(final int api) {
		if (api != Opcodes.ASM7 && api != Opcodes.ASM6 && api != Opcodes.ASM5 && api != Opcodes.ASM4) {
			throw new IllegalArgumentException("Unsupported api " + api);
		}
		this.api = api;
	}

	/**
	 * Visits a formal type parameter.
	 *
	 * @param name the name of the formal parameter.
	 */
	public void visitFormalTypeParameter(final String name) {}

	/**
	 * Visits the class bound of the last visited formal type parameter.
	 *
	 * @return a non null visitor to visit the signature of the class bound.
	 */
	public SignatureVisitor visitClassBound() {
		return this;
	}

	/**
	 * Visits an interface bound of the last visited formal type parameter.
	 *
	 * @return a non null visitor to visit the signature of the interface bound.
	 */
	public SignatureVisitor visitInterfaceBound() {
		return this;
	}

	/**
	 * Visits the type of the super class.
	 *
	 * @return a non null visitor to visit the signature of the super class
	 *         type.
	 */
	public SignatureVisitor visitSuperclass() {
		return this;
	}

	/**
	 * Visits the type of an interface implemented by the class.
	 *
	 * @return a non null visitor to visit the signature of the interface type.
	 */
	public SignatureVisitor visitInterface() {
		return this;
	}

	/**
	 * Visits the type of a method parameter.
	 *
	 * @return a non null visitor to visit the signature of the parameter type.
	 */
	public SignatureVisitor visitParameterType() {
		return this;
	}

	/**
	 * Visits the return type of the method.
	 *
	 * @return a non null visitor to visit the signature of the return type.
	 */
	public SignatureVisitor visitReturnType() {
		return this;
	}

	/**
	 * Visits the type of a method exception.
	 *
	 * @return a non null visitor to visit the signature of the exception type.
	 */
	public SignatureVisitor visitExceptionType() {
		return this;
	}

	/**
	 * Visits a signature corresponding to a primitive type.
	 *
	 * @param descriptor the descriptor of the primitive type, or 'V' for
	 *            {@code void} .
	 */
	public void visitBaseType(final char descriptor) {}

	/**
	 * Visits a signature corresponding to a type variable.
	 *
	 * @param name the name of the type variable.
	 */
	public void visitTypeVariable(final String name) {}

	/**
	 * Visits a signature corresponding to an array type.
	 *
	 * @return a non null visitor to visit the signature of the array element
	 *         type.
	 */
	public SignatureVisitor visitArrayType() {
		return this;
	}

	/**
	 * Starts the visit of a signature corresponding to a class or interface
	 * type.
	 *
	 * @param name the internal name of the class or interface.
	 */
	public void visitClassType(final String name) {}

	/**
	 * Visits an inner class.
	 *
	 * @param name the local name of the inner class in its enclosing class.
	 */
	public void visitInnerClassType(final String name) {}

	/**
	 * Visits an unbounded type argument of the last visited class or inner
	 * class type.
	 */
	public void visitTypeArgument() {}

	/**
	 * Visits a type argument of the last visited class or inner class type.
	 *
	 * @param wildcard '+', '-' or '='.
	 * @return a non null visitor to visit the signature of the type argument.
	 */
	public SignatureVisitor visitTypeArgument(final char wildcard) {
		return this;
	}

	/**
	 * Ends the visit of a signature corresponding to a class or interface type.
	 */
	public void visitEnd() {}
}
